129 lines
3 KiB
ArmAsm
129 lines
3 KiB
ArmAsm
.proc circle_help ; This is because jmp cant jump that long!
|
|
.include "circle.inc"
|
|
|
|
|
|
;;We have named the parts of the circle as such.
|
|
;; |
|
|
;; qbb | qab
|
|
;; |
|
|
;; qba | qaa
|
|
;;---------------X-----------------> X
|
|
;; qca | qda
|
|
;; |
|
|
;; qcb | qdb
|
|
;; |
|
|
;; v Y
|
|
;; The q stands for quarter, whe have 4 quarter, and each quarter is split into 2
|
|
|
|
|
|
draw_qaa:
|
|
LDA byte_to_paint ;A byte containing a single 1. Coresponds to X position in the chunk.
|
|
ORA (btp_mem_pos), Y
|
|
STA (btp_mem_pos), Y
|
|
|
|
;; something is wrong | well isue for another time
|
|
draw_qcb:; xy swaped
|
|
STY temp
|
|
STX temp_
|
|
LDA byte_to_paint
|
|
STA temp__
|
|
|
|
LDY #$00
|
|
jmp goto_loop
|
|
loop:
|
|
INY
|
|
goto_loop:
|
|
asl byte_to_paint; lsr asl
|
|
BCC loop
|
|
STY temp___
|
|
|
|
|
|
LDX temp
|
|
LDA binary_factor, X; (see END.s)
|
|
|
|
|
|
LDY temp___
|
|
ORA (btp_mem_pos_swop), Y
|
|
STA (btp_mem_pos_swop), Y;
|
|
|
|
|
|
draw_qab: ;xy swoped + mirroring
|
|
|
|
LDA btp_mem_pos_center_two
|
|
SBC btp_mem_pos_swop
|
|
STA btp_mem_pos_inv
|
|
LDA btp_mem_pos_center_two + 1
|
|
SBC btp_mem_pos_swop + 1
|
|
STA btp_mem_pos_inv + 1
|
|
|
|
LDY temp___
|
|
SEC
|
|
LDA #$07
|
|
SBC temp___
|
|
TAY
|
|
|
|
LDX byte_to_paint
|
|
LDA inverse_factor_value, X;; (see END.s) TAX ;; A is saved to x because qba use this as well
|
|
ORA (btp_mem_pos_inv), Y
|
|
STA (btp_mem_pos_inv), Y
|
|
|
|
|
|
LDY temp
|
|
LDX temp_
|
|
LDA temp__
|
|
STA byte_to_paint
|
|
draw_qda:
|
|
;; inverted Y, this is shared with qca
|
|
STY temp
|
|
LDA #$07
|
|
SEC
|
|
SBC temp
|
|
TAY
|
|
|
|
|
|
LDA byte_to_paint
|
|
ORA (btp_mem_pos_inv_y), Y
|
|
STA (btp_mem_pos_inv_y), Y
|
|
|
|
draw_qca: ;;mirror technique
|
|
SEC
|
|
;;C = 1 beacause the branching to while_x_bigger_then_y and SEC on first ittteration.
|
|
LDA btp_mem_pos_center_two
|
|
SBC btp_mem_pos
|
|
STA btp_mem_pos_inv
|
|
LDA btp_mem_pos_center_two + 1
|
|
SBC btp_mem_pos + 1
|
|
STA btp_mem_pos_inv + 1
|
|
|
|
;; calculate byte_to_paint_inv 00000001 --> 10000000, 00000010 --> 01000000 ... etc
|
|
;; uses a table!
|
|
STX temp_
|
|
LDX byte_to_paint
|
|
LDA inverse_factor_value, X;; (see END.s)
|
|
TAX ;; A is saved to x because qba use this as well
|
|
|
|
; A = byte_to_paint_inv
|
|
ORA (btp_mem_pos_inv), Y
|
|
STA (btp_mem_pos_inv), Y
|
|
|
|
;;Recover the Y value (we changed it because evrything is inverted)
|
|
LDY temp
|
|
|
|
draw_qba: ;;mirror_technique
|
|
SEC
|
|
LDA btp_mem_pos_center_two
|
|
SBC btp_mem_pos_inv_y
|
|
STA btp_mem_pos_inv
|
|
LDA btp_mem_pos_center_two + 1
|
|
SBC btp_mem_pos_inv_y + 1
|
|
STA btp_mem_pos_inv + 1
|
|
|
|
TXA
|
|
LDX temp_
|
|
|
|
; A = byte_to_paint_inv
|
|
ORA (btp_mem_pos_inv), Y
|
|
STA (btp_mem_pos_inv), Y
|
|
|
|
RTS
|
|
.endproc
|